/**
 * JDBM LICENSE v1.00
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. The name "JDBM" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Cees de Groot.  For written permission,
 *    please contact cg@cdegroot.com.
 *
 * 4. Products derived from this Software may not be called "JDBM"
 *    nor may "JDBM" appear in their names without prior written
 *    permission of Cees de Groot.
 *
 * 5. Due credit should be given to the JDBM Project
 *    (http://jdbm.sourceforge.net/).
 *
 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2001 (C) Alex Boisvert. All Rights Reserved.
 * Contributions are Copyright (C) 2001 by their associated contributors.
 *
 */

package com.sunchangming.stmdb.helper;

/**
 * Miscelaneous conversion utility methods.
 * 
 * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a>
 * @version $Id: Conversion.java,v 1.3 2002/05/31 06:33:20 boisvert Exp $
 */
public class Conversion {

	/**
	 * Convert a string into a byte array.
	 */
	public static byte[] convertToByteArray(String s) {
		try {
			// see the following page for character encoding
			// http://java.sun.com/products/jdk/1.1/docs/guide/intl/encoding.doc.html
			return s.getBytes("UTF8");
		} catch (final java.io.UnsupportedEncodingException uee) {
			uee.printStackTrace();
			throw new Error("Platform doesn't support UTF8 encoding");
		}
	}

	/**
	 * Convert a byte into a byte array.
	 */
	public static byte[] convertToByteArray(byte n) {
		n = (byte) (n ^ ((byte) 0x80)); // flip MSB because "byte" is signed
		return new byte[] { n };
	}

	/**
	 * Convert a short into a byte array.
	 */
	public static byte[] convertToByteArray(short n) {
		n = (short) (n ^ ((short) 0x8000)); // flip MSB because "short" is
											// signed
		final byte[] key = new byte[2];
		pack2(key, 0, n);
		return key;
	}

	/**
	 * Convert an int into a byte array.
	 */
	public static byte[] convertToByteArray(int n) {
		n = (n ^ 0x80000000); // flip MSB because "int" is signed
		final byte[] key = new byte[4];
		pack4(key, 0, n);
		return key;
	}

	/**
	 * Convert a long into a byte array.
	 */
	public static byte[] convertToByteArray(long n) {
		n = (n ^ 0x8000000000000000L); // flip MSB because "long" is signed
		final byte[] key = new byte[8];
		pack8(key, 0, n);
		return key;
	}

	/**
	 * Convert a byte array (encoded as UTF-8) into a String
	 */
	public static String convertToString(byte[] buf) {
		try {
			// see the following page for character encoding
			// http://java.sun.com/products/jdk/1.1/docs/guide/intl/encoding.doc.html
			return new String(buf, "UTF8");
		} catch (final java.io.UnsupportedEncodingException uee) {
			uee.printStackTrace();
			throw new Error("Platform doesn't support UTF8 encoding");
		}
	}

	/**
	 * Convert a byte array into an integer (signed 32-bit) value.
	 */
	public static int convertToInt(byte[] buf) {
		int value = unpack4(buf, 0);
		value = (value ^ 0x80000000); // flip MSB because "int" is signed
		return value;
	}

	/**
	 * Convert a byte array into a long (signed 64-bit) value.
	 */
	public static long convertToLong(byte[] buf) {
		long value = ((long) unpack4(buf, 0) << 32)
				+ (unpack4(buf, 4) & 0xFFFFFFFFL);
		value = (value ^ 0x8000000000000000L); // flip MSB because "long" is
												// signed
		return value;
	}

	static int unpack4(byte[] buf, int offset) {
		final int value = (buf[offset] << 24)
				| ((buf[offset + 1] << 16) & 0x00FF0000)
				| ((buf[offset + 2] << 8) & 0x0000FF00)
				| ((buf[offset + 3] << 0) & 0x000000FF);

		return value;
	}

	static final void pack2(byte[] data, int offs, int val) {
		data[offs++] = (byte) (val >> 8);
		data[offs++] = (byte) val;
	}

	static final void pack4(byte[] data, int offs, int val) {
		data[offs++] = (byte) (val >> 24);
		data[offs++] = (byte) (val >> 16);
		data[offs++] = (byte) (val >> 8);
		data[offs++] = (byte) val;
	}

	static final void pack8(byte[] data, int offs, long val) {
		pack4(data, 0, (int) (val >> 32));
		pack4(data, 4, (int) val);
	}

	/**
	 * Test static methods
	 */
	public static void main(String[] args) {
		byte[] buf;

		buf = convertToByteArray(5);
		System.out.println("int value of 5 is: " + convertToInt(buf));

		buf = convertToByteArray(-1);
		System.out.println("int value of -1 is: " + convertToInt(buf));

		buf = convertToByteArray(22111000);
		System.out.println("int value of 22111000 is: " + convertToInt(buf));

		buf = convertToByteArray(5L);
		System.out.println("long value of 5 is: " + convertToLong(buf));

		buf = convertToByteArray(-1L);
		System.out.println("long value of -1 is: " + convertToLong(buf));

		buf = convertToByteArray(1112223334445556667L);
		System.out.println("long value of 1112223334445556667 is: "
				+ convertToLong(buf));
	}

}
